Wire ropes are commonly used in high tension and bending stress applications. These applications include control cables (aircraft, automobile, motorcycle, and bicycle), lifting/hoisting/rigging and winching (forestry, defense department, fishing, marine, underground mining, structural, industrial and construction lifting, rigging and winching, oil and gas mining, utilities, elevator, crane, agriculture, aircraft, consumer products, office equipment, sporting goods, fitness equipment), running ropes (tramway, funiculars, ski lift, bridges, ropeways, shuttles), electrical wire or current carrying wires (flexible copper wires/cables (including ribbon cables, printed circuit board conductors), marine and fishing (towing, mooring, slings), navy and us defense department (arrestor cable, underway replenishment cables), reinforcement of rubber and plastics (tires, belts, hoses), and electrical mechanical applications (umbilicals for remote operated vehicles, fiber optic cables, tethers, plow trenches, tow rigs, seismic arrays).
The primary failure mechanisms for wire ropes are abrasion and bending fatigue. Rope life has been extended by altering the design to meet the requirements of the application. For example, the lay of a rope, that is the placement of the wires and strands during construction, can be left or right, regular, lang, or alternate. Furthermore, the strands can be constructed in various combinations of wires and wire sizes to enhance durability. Ropes are also lubricated to extend their service life.
Grease decreases frictional wear and inhibits corrosion. Such lubricants, however, break down over time and require costly and time-consuming replacement. Effective replenishment of lubricant is also a problematic process.
Fibers, such as polypropylene, nylon, polyesters, polyvinyl chloride, and other thermoplastics and thermoset materials and high modulus materials have been added to the rope construction, typically in the core. The fibers have typically been used to carry lubricants in an attempt to increase the abrasion resistance of wire ropes and for corrosion resistance. The use of these fibers to replace metal wire can come at the expense of weakening the rope and have not been put to widespread use because of insufficient durability improvements.
Incorporating pre-formed polymeric inserts into the construction of wire ropes has been proposed to increase rope life and reduce vibration and torsional forces within the rope. These inserts are made to exacting shapes and dimensions and require special care during rope manufacturing. They are relatively complicated and expensive to prepare and are difficult to accurately position in forming the rope.
Wire ropes still suffer from inadequate durability. The object of the present invention is to improve the life of wire ropes.